Currently the control of controllable devices, especially consumer devices like VCRs, TV sets or CD players, is performed by the use of one or more remote control units which deliver the information or commands in most cases via an IR (infrared) beam. The feedback of the chosen device to the user is normally provided via an optical display of the action resulting from the command. Other man-machine interfaces are known, for example when a computer controls a certain amount of devices, which need not necessarily be consumer devices, wherein the interface between the man and the machine is usually provided via a keyboard, a mouse and a screen, with which a central processing unit controls the connected devices via programs.
Because of the increasing number and complexity of the consumer devices the above man-machine interfaces are not very user-friendly. One way to enhance the user-friendliness of a user interface is to increase the number of senses that the user interface appeals to. One of the most promising natural input/output possibility is the speech interface.
Voice can be used both for the command, with speech recognition, and for the feedback through voice synthesis. The current applications using voice synthesis are designed for an environment managing only one device. In this known case the device is equipped with a speech recognition and a voice synthesis system. Such solutions are known for example from the field of robotics. In contrast, a consumer household usually comprises a plurality of different devices, which can be controllable in principle. This poses the problem of how to identify the different controllable devices in a dialogue between the user and the devices, if a voice-based man-machine interface is used.